Process for increasing the breaking strength of staple fibers



PROCESS FOR INCREASING THEBREAKING STRENGTH F STAPLE NoDrawing. Application December 16,1952, Serial No. 326,369

Claims. (Cl. 117--7) (Granted under Title 35, U. S. Code (1952), see. 266) A non-exclusive, irrevocable, royalty-free license in the invention herein described, for all governmental purposes, throughout the world, with the power to grant sub-licenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to the treatment of twisted strands such as yarns, threads, ropes, and the like, of staple textile fibers of vegetable, animal, and synthetic origin. More particularly, this invention provides a combined chemical and mechanical treatment which increases the breaking strength of such strands.

In general, in accordance with the process of this invention, such strands are impregnated with a colloidal aqueous dispersion of silica, the wet strands are subjected to a tension intermediate between the normal tension used in conventional textile strand processing procedures, such as slashing, and the breaking tension of the strand, and the so-treated strands are dried.

The process can suitably be applied to twisted strands of staple textile fibers, including fibers of cotton, wool, rayon, mixtures thereof; cellulosic fibers, such as cellulose nitrate, cellulose acetate, viscose, cuprammonium rayon and high tensile strength rayon; protein fibers, such as silk and fibers made from the casein in milk; synthetic fibers, such as fibers made of the copolymer of vinyl chloride and vinylidine chloride, the copolymer of adipic acid and liexarnethylene diamine, the copolymer of vinyl chloride and vinyl acetate, and glass fibers; and mixtures or blends of any two or more of the above fibers. The process is preferably applied to cotton yarn.

The twisted strands can suitably be impregnated by spraying, immersion, wiping, or the like treatments, with or without the assistance of padding or squeeze rolls or other types of extracting equipment. Impregnating by immersion, followed by padding to a wet pickup of about 100%, is preferred.

Colloidal aqueous dispersions of silica which can suitably be used include solutions and salts substantially free of silica gel described in U. S. Patents 2,244,325; 2,285,449;

2,285,477; and 2,375,738, and the like. The silica content of the dispersions can suitably range from about 1 to 30%. The use of a solution containing 15-30% silica, such as is presently marketed under the trade name Syton or Ludox is preferred, either with or without further dilution with water.

Wetting agents can suitably be incorporated in the aqueous dispersions of silica to decrease the interfacial tension between the fibers and the liquid. Wetting agents which can suitably be used include the sodium salts of alkylated aryl sulfonates such as sodium octyl benzene sulfonate and sodium decyl benzene sulfonat'e, sodium lauryl sulfate, the sodium salt of methyl stearamide ethionic acid, dioctyl sodium sulfosuccinate and the like. Wetting agents, where they are used, are preferably used in a concentration of from about 0.1 to 5% of the silica dispersion. The use of about 0.1% of an alkylated naphthalene sulfonate, such as is presently marketed under the trade name Nekal BX, is preferred.

United States Patent The tensioning of the strands while they are wet with i the aqueous dispersion of silica can suitably be accomplished by means of any of the conventional strand tensioning procedures. The amount of tension applied is preferably just short of the breaking tension. The breaking tension of a given strand varies with the size, quality, and structure of the strand and can readily be determined by conventional procedures.

After the strands have been impregnated and tensioned while wet, the strands can suitably be dried to any desired moisture content with or without tension. Drying, with tension, to a moisture content of from about 1 to 10% is preferred.

The following examples areillustrative of the invention:

Example I A sample of 9s/ 3 cotton yarn was impregnated with a dispersion of 10% silica solids (Syton W-20, Monsanto Chemical Co.) and 0.1% of a wetting agent (Nekal BX, General Dyestuff Co.), the excess liquor being removed by padding so as to yield a wet-pickup. The yarn, while still wet, was stretched under constant tension on a Kidde laboratory unit, and dried while still under tension. An equivalent yarn sample was treated with silica sol and wetting agent in the same manner as previously described, but with the omission of any tensioning either in the wet or dry state. A comparison of the breaking strength of the two treated samples with an untreated control sample indicated the following:

Untreated 5.55 lbs.

Syton alone 6.55 lbs., 18.02% increase over untreated.

Syton plus stretching 8.15 lbs., 46.85% increase over untreated.

Example II A sample of 9s/ 3 cotton yarn was impregnated with a dispersion of 10% silica solids (Syton W-20, Monsanto Chemical Co.), the excess liquor being removed by padding so as to yield approximately 100% Wet-pickup. A small amount of wetting agent was added to the impregnating bath (0.1% Nekal BX, General Dyestufi (10.). The yarn, while still Wet, was stretched under constant tension, and dried while still under tension on a Kiddo laboratory unit. An equivalent yarn sample was stretched and dried under the same conditions as previously described, with the exception that water was substituted for the Syton. A comparison of the breaking strength of the treated yarn with an untreated control sample indicated the following:

Untreated 5.12 lbs.

Stretched with water 6.92 lbs., 35.16% increase over untreated.

Stretched with Syton 8.76 lbs., 71.09% increase over untreated.

I claim:

1. A process for increasing the breaking strength of strands of staple fibers comprising: impregnating a twisted strand of staple textile fiber with a colloidal aqueous dispersion of silica, subjecting the wet strand to a tension intermediate between the normal tension used in conventional textile strand processing procedures and the breaking tension of the strand, and drying the so-treated strand intermediate between the normal tension used in conventional textile strand processing procedures and the breaking tension of the strand, and drying the so-treated strand without tension.

3. A process for increasing the breaking strength of strands of staple fibers comprising: impregnating a twisted strand of staple textile fiber with a colloidal aqueous dispersion of silica together with a wetting agent, subjecting the wet strand to a tension intermediate between the normal tension used in conventional textile strand processing procedures and the breaking tension of the strand, and drying the so-treated strand.

4. The process of claim 1 in which the staple textile fiber is cotton.

5. The process of claim 3 in which the staple textile fiber is cotton.

References Cited in the file of this patent UNITED STATES PATENTS 2,220,958 Jennings Nov. 12, 1940 2,438,968 Feild et a1 Apr. 6, 1948 2,485,153 Henning et al. Oct. 18, 1949 2,527,329 Powers et a1 Oct. 24, 1950 

1. A PROCESS FOR INCREASING THE BREAKING STRENGTH OF STRANDS OF STAPLE FIBERS COMPRISING: IMPREGNATING A TWISTED STRAND OF STAPLE TEXTILE FIBER WITH A COLLOIDAL AQUEOUS DISPERSION OF SILICA, SUBJECTING THE WET STRAND TO A TENSION INTERMEDIATE BETWEEN THE NORMAL TENSION USED IN CONVENTIONAL TEXTILE STRAND PROCESSING PROCEDURES AND THE BREAKING TENSION OF THE STRAND, AND DRYING THE SO-TREATED STRAND UNDER TENSION. 